Added comment to test_create_letter.
Added comment to test_create_letter.

UWPCE-PythonCert/IntroPython2016,weidnem/IntroPython2016,UWPCE-PythonCert/IntroPython2016,UWPCE-PythonCert/IntroPython2016,weidnem/IntroPython2016,weidnem/IntroPython2016